The present invention has for its object a device intended to be placed in the eye to treat presbyopia or other ocular disorders related to an eye accommodation defect.
In order to understand more readily the problem to be solved, accompanying FIG. 1 shows a half-view of an eye in vertical section. This Figure shows the cornea 1, the internal wall of the eye 4 with its ciliary body 6 and the iris 8 which defines the pupil 9 of the eye. This Figure also shows the sulcus which constitutes a groove between the ciliary body 6 and the iris 8 as well as the crystalline lens 14 with its capsular sac 16. The crystalline lens 14, or, more precisely, its capsular sac 16 is connected to the wall 4 of the eye by an assembly of muscles called zonules constituted by fibrils. These fibrils have one end 18a which is connected to the periphery of the capsular sac 16 and another end which is embedded in the ciliary body 6. When the eye is in a normal state, the controlled contractions of the zonules 18 provoke modification of the radii of curvature of the crystalline lens 14, thus allowing accommodation of the eye as a function of the distance at which the object to be looked at is located.
It has been demonstrated that the ageing of the eye tended to produce an increase in the outer dameter of the crystalline lens. As a result, the zonules become xe2x80x9ctoo longxe2x80x9d and are xe2x80x9crelaxedxe2x80x9d and the impulses applied to the fibrils of the zonules no longer enable the latter to act on the crystalline lens to provoke accommodation.
It has also been demonstrated that it is the traction exerted on the capsular sac by the zonules which makes it possible to increase the optical power of the crystalline lens, by provoking a reduction of the radius of curvature of its posterior face.
An object of the present invention is to provide a device adapted to be implanted in the eye, which makes it possible to render the zonules active again in order to allow accommodation despite the increase in the diameter of the crystalline lens.
To attain that object, according to the invention, the device for treating presbyopia or other ocular disorder related to an eye accommodation defect is characterized in that it comprises a piece having substantially the shape of at least a ring portion with an axis of revolution and a first edge disposed on a circle of diameter D1 included between 12.5 and 13.5 mm and a second edge disposed on a circle of diameter D2 included between 9.5 and 10.5 mm, said edges being offset in the direction of said axis of revolution by a length h included between 0.5 and 2.5 mm, said first edge being designed to rest, over at least part of its length, on part of the internal wall of the eye and said second edge being capable of being pressed against a median zone of the zonules of the crystalline lens, whereby is obtained a displacement of said median zone of said zonules stressing them and enabling them to cause the deformation of the crystalline lens under the effect of stimulations applied to said zonules.
It will be understood that the ring or ring portion positioned inside the eye rests by its outer edge in the zone of the ciliary sulcus while its other inner edge applied against the median zone of the zonules provokes the rearward displacement of this median zone of the zonules as well as of the crystalline lens. This displacement makes it possible to obtain a new stressing of the zonules which will thus be rendered active again when the fibrils which constitute them are excited.
According to a first embodiment of the invention, the ring is closed and in that case it is made of a supple biocompatible material in order to allow insertion of the ring inside the eye. According to a second embodiment of the invention, the ring is open and, in that case, it may be made of a rigid biocompatible material such as for example PMMA.
In the present text, it must be specified that xe2x80x9csupple materialxe2x80x9d is understood to mean materials currently used for manufacturing intraocular implants in particular and which are typically constituted by polyHEMAs or by silicon gels. The term xe2x80x9crigid materialxe2x80x9d must be understood to mean translucent biocompatible materials presenting a low coefficient of elasticity and of which the most well known is PMMA.